A leading US energy executive has been barred from the board of ExxonMobil over allegations he colluded with Opec+ to raise oil prices. Scott Sheffield, the former chief executive of Pioneer Natural Resources, coordinated with US shale oil producers to restrict output and raise energy prices, the US Federal Trade Commission (FTC) alleged. The FTC also claimed he used that position of influence to “align oil production across the Permian Basin in West Texas and New Mexico with Opec+”, the organisation dominated by Middle Eastern countries and Russia. FTC said the collaboration between Opec and American rivals would have decreased oil production and pushed up fuel prices. The US watchdog made the claims as it gave the go-ahead for ExxonMobil’s $60bn (£47.9bn) purchase of Pioneer but effectively blocked Mr Sheffield from further involvement. Kyle Mach, deputy director of the FTC’s Bureau of Competition, told Reuters: “Mr. Sheffield’s past conduct makes it crystal clear that he should be nowhere near Exxon’s boardroom.” Mr Sheffield and Pioneer reject the allegations. In a statement, they said the regulator had “a fundamental misunderstanding of the US and global oil markets and misreads the nature and intent of Mr. Sheffield’s actions”. A spokesman added: “During...